Ion Temperature Measurements and Impurity Radiation in HSX

Doppler broadening of impurity line radiation from HSX plasmas is measured in order to calculate the temperatures of ions in the plasma. Impurity content and temperature measurements are primarily being used at present to examine the plasma under different wall conditioning methods. When only glow discharge cleaning has been employed to condition the stainless steel first wall iron emissions are observed in 1 T operation, with a lack of density control. The correlation between edge impurity content and density control is examined for both boronized and carbonized wall conditions. Carbonized walls give good control with reduced oxygen signals and generally show lower radiated power than boronized discharges. These temperature measurements can be used as an indicator of the temperature of the primary ion species (typically hydrogen) in various magnetic configurations, and also must be known to correctly measure the plasma rotation velocity using the charge exchange recombination spectroscopy system, which is currently being implemented on HSX.